BIORESOURCES CORE: Resources for FSHD research and clinical trials Abstract Access to well characterized patient biological samples was critical for the recent advances in our understanding of the underlying disease mechanisms in FSHD. The continued availability of these finite resources remains critical for the current scientific projects 1-3. Moreover, as clinical trials in FSHD in the near future become a reality, the need for relevant outcome measures becomes a priority. The major aims of the Scientific Core are to provide the scientific projects with the necessary, clinically and genotypically well characterized biological resource, and to work in parallel with the scientific projects on clinical trial preparedness. The specific aims of the Scientific Core accomplish these goals by: Aim1 generating the necessary tissue and cell lines from subjects with FSHD1, FSHD2 and normal controls; Aim 2, generating a large set of FSHD and control sera and investigating identified DUX4 targets in muscle tissue for potential biomarkers as well as test and validate promising clinical outcome measures. Together, these aims will not only provide the necessary biological resources to meet the needs of all three PO1 scientific projects, but will also assist in the development of the tools necessary for the conduct of future clinical trials in FSHD. 1